HIV-1 infection and AIDS disproportionately affect people in resource-limited settings. Although the neurologic complications of HIV infection are well-documented in western countries, the neurologic impact of HIV infection in China is unclear. HIV-1 transmission via drug abuse and sexual intercourse is primarily responsible for the current HIV/AIDS epidemic in China. This current proposal is written in response to the RFA-DA-08-005 entitled "International research collaborations to study HIV/AIDS and drug abuse (R21) to explore the feasibility of addressing the relationship between drug abuse and NeuroAIDS in China, a resource-limited developing country with a rapidly increasing number of HIV-infected individuals in the world. Our long-term goal is to better characterize the neurologic complications associated with HIV infection in China and their response to treatment, and to better understand their viral and host correlates. This study will build upon an established collaboration between HIV NeuroAIDS investigators at Indiana University School of Medicine in the United States and a diverse group of physician scientists at the First Affiliated Hospital of Xi'an Jiaotong University Medical College in Xi'an, China. We have worked together and identified and recruited a cohort of HIV+ and HAART naive individuals. For this one-year R21 application, we propose: (1) To establish a repository of cerebrospinal fluid (CSF), plasma, and peripheral blood mononuclear cells (PBMCs) from the cohort of HIV+ and HAART naive individuals; (2) To evaluate neurologic manifestations of the cohort of HIV+ and HAART naive individuals; (3) To evaluate neurocognitive impairment (NCI) of the cohort of HIV+ and HAART naive individuals. Comparison of the neurology and neurobehaviors of these patients with or without a history of drug abuse will allow us to address the roles of drug abuse in NeuroAIDS in China. These studies will also help to train NeuroAIDS researchers and build the drug abuse/NeuroAIDS research capacity in China. Furthermore, these studies shall add to our understanding of the neurobehavioral complications of HIV diseases in China and the viral and host correlates to NeuroAIDS, and ultimately lead to better informed clinical management of the affected population. [unreadable] [unreadable] HIV-1 infection often causes a number of brain diseases and affects the ability of people to care for themselves and thus the quality of their daily life. The social and economic impact can not be overemphasized. The current study seeks to have a better understanding of the prevalence and nature of these diseases in the selected population. [unreadable] [unreadable] [unreadable]